Tang breakoff tool having spring actuated impact means



May 28, 1968 R. E. WALLER TANG BREAKOFF 1:001. HAVING srnme ACTUATED IMPACT MEANS Filed Oqt. 20, 19.66

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United States Patent Oflice 3,385,380 TANG BREAKOFF TOOL HAVING SPRING ACTUATED IMPACT MEANS Richard E. Waller, Erie, Pa., assignor, by mesne assignments, to Vare Corporation, New York, N.Y., a corporation of Delaware Filed Oct. 20, 1966, Ser. No. 588,089 6 Claims. (Cl. 173-119) ABSTRACT OF THE DISCLOSURE A tool for breaking off a tang at the end of an inserted thread is composed of telescoped tube sections the inner tube having a plunger and a piston which are spaced apart by a spring with the piston urged toward the plunger by a spring compressed by the movement of the outer sleeve over the inner sleeve when the plunger is in engagement with the tang to produce a hammer blow on the plunger when the piston is released.

In the copending application of Raymond L. Thurston et al., Ser. No. 570,935, filed Aug. 8, 1966, for a Helical Coil Insert Tool, and assigned to the assignee of the present invention, a tool is illustrated for applying a C011 of wire to a thread of an aperture to provide a hard thread in a soft material. The coil had a tang extending inwardly on its diameter, which was engaged by the tool to have the coil rotate therewith when being reduced in diameter as the turns advanced over the thread in the aperture. At the end of the operation the tool was withdrawn, but the tang remained within the aperture. In deadend holes, the presence of the tang was not objectionable, but in holes where a screw was to pass beyond the thread the tang must be removed, otherwise it limited the degree of advancement of the screw on the thread.

The present invention relates to a tool for removing the tang on the inner end of the coil by applying the striking end of a tool against the tang with a low spring pressure and thereafter operating the tool to deliver a sharp blow to snap off the tang. The tang has a notch cut therein at the base of the thread so that it will readily break when a sharp blow is applied to the end of the tool. The tool has a pair of telescoping sleeves, the bottom sleeve having a piston within the upper end and a plunger near the lower end, from which it extends. A pair of springs are located within the sleeves, one between the piston and plunger and a heavier spring between the piston and closed end of the outer sleeve. A third spring is employed between the sleeves which along with the pair of springs extend the sleeves and plunger outwardly of each other. When a tang is to be broken from the Wire of the thread, the end of the plunger is inserted in the aperture against the tang and the end of the inner sleeve adjacent thereto has a rubber end which is moved against the surface of the element having the thread therein. A light spring is employed for urging the plunger outwardly when reacting against the piston so as not to bend the tang when engaged therewith. A substantially heavier spring engages the opposite end of the piston and the remote closed end of the outer sleeve. Upon the downward movement of the outer sleeve, the compressing of the heavier spring will move the piston downwardly until a shoulder thereon engages a pair of balls retained against the piston by the inner surface of the outer sleeve. The striking piston is retained in this position as the heavier spring is further tensioned on the continued movement of the outer sleeve near the end of which an area having a larger diameter permits the balls to move away from the piston a sufiicient distance to release the piston which is driven toward the plunger while compressing the 3,385,380 Patented May as, 1968 lighter spring. The piston strikes the plunger with the same amount of force each operation which is sufficient to snap the tang from the wire forming the thread and clear the aperture for the passage of a screw beyond the end of the wire thread.

Accordingly, the main objects of the invention are: to provide a tool having a plunger engaging the tang of a thread with increasing pressure as pressure is built up on a striking piston before it is released; to provide a tool with inner and outer telescoped sleeves and with a reciprocal plunger extending from the inner sleeve which also contains a striking piston which is spaced therein by springs engaging opposite ends thereof; to provide a tool with a plunger which engages a tang of a thread within an aperture with a minimum force before a piston is released to strike a substantial blow after a predetermined pressure has been built up thereon, and in general, to provide a tool for removing a tang from within a threaded aperture which is simple in construction, positive in operation and economical of manufacture.

Other objects and features of novelty of the invention will be specifically pointed out or will become apparent when referring, for a better understanding of the invention, to the following description, taken in conjunction with the accompanying drawing, wherein:

FIGURE 1 is a sectional view of a tool for removing the tang of a thread, shown in extended position;

FIG. 2 is a view of the structure of FIG. 1 after the end of the plunger engages the tang and the body engages the surface of the element having the threaded aperture and with the driving spring near its fully compressed position, and

FIG. 3 is an enlarged broken sectional view of the structure of FIG. 2, as viewed within the circle 3 thereof.

Referring to the drawing, an element 11 is illustrated as having a threaded aperture 12 containing a coil spring 13 of wire to form a thread of hard material within the aperture. The end 14 of the coiled Wire has a notch 15 at its base adjacent to the coil. A tool 15 of the present invention is employed for removing the tang 14 by applying a sharp blow thereto. The tool has an inner sleeve 17 over which an outer sleeve 18 telescopes for movement relative to each other. The inner sleeve 17 has a plunger 19 having a striking end extending from the end of the sleeve. A piston 21 is disposed in the upper end of the sleeve 17 being spaced from the plunger 19 by a light spring 22. A heavy spring 23 engages the upper end of the piston and the closed end 20 of the outer sleeve 18.

The piston 21 has a projecting flange 24 on its upper end containing oppositely disposed truncated conical surfaces. Tapered apertures 25 are provided through the wall of the inner sleeve 17, in each of which a ball 26 is disposed. In FIG. 1, it will be noted that the inner and outer sleeves 17 and 18 are in maximum extended position. A collar 27 threaded on the end of a sleeve 18 is engaged with a shoulder 28 on the outer wall of the sleeve 17. The assuming of this position is caused by the action of the springs 22 and 23 which react against the plunger 19 and the closed end of the sleeve 18. A third spring 23a reacts between the closed end 20 and the adjacent end portion of the sleeve 17. The plunger 19 is urged against a shoulder 29 near the bottom of the sleeve 17 with the piston floated in the upper part thereof. In this arrangement the flange 24 is out of engagement with the balls 26 which are free to move into engagement with an inner wall section 31 of the outer sleeve 18 of greater diameter than the outside diameter of the inner sleeve 17.

In FIG. 2, it will be noted that the end of the plunger 19 is in engagement with the tang 14 and that a rubber end 32 of the sleeve 17 has engaged the element 11 containing the aperture and the coiled wire thread 13. The

balls 26 have been engaged by the wall section 34 of the outer sleeve 18 which has a diameter substantially that of the outside diameter of the inner sleeve 17. This moved the balls inwardly in position to engage the lower sloping surface of the flange 24 when the sleeve 18 is moved downwardly. As the sleeve 18 continues to be moved downwardly, a wall section 35 in the upper part of the sleeve 18 having the same diameter as that of the wall section 31, will permit the balls 26 to move therein when cammed by the engaged conical surface of the flange 247 The movement of the balls from the flange 24 releases the piston 21 which is urged downwardly by the compressed spring 23 with a considerable force. The end of the piston 21 will strike the upper end of the plunger 19 and the shock delivered from the end thereof to the tang 14 will cause the latter to snap off at the notch 15. This will permit the thread of a screw to pass over the entire length of the thread 13.

Upon the upper movement of the outer sleeve 18 by the springs 23 and 23a, the piston will move upwardly until the top truncated conical surface of the flange 24 engages the balls 26 and cams them outwardly against the wall 31. The flange 24 will then pass the balls and assume the position illustrated in FIG. 1 with the movement of the sleeves 17 and 18 away from each other being assisted by the spring 23a.

It will be noted that the closed end 20 of the outer sleeve 13 has a threaded plug 38 screwed into the internal thread 39 in the end of the sleeve. The plug 38 as Well as the collar 27 may be locked in position by a securing element herein illustrated by a friction plug 40 of conventional form. The plunger 19 and the piston 21 have sufiicient clearance with the walls of the sleeves 17 and 18 as to eliminate any friction therebetween so that a like blow will be delivered each operation.

It will thus be seen that the tang 14 can be broken from the end of the thread 13 by applying the end of a plunger 19 against the tang with a light pressure and the resilient end 32 of the inner sleeve 17 against the element 11 containing the threaded aperture. Thereafter, the downward movement of the outer sleeve 18 will release the piston 21 after a predetermined spring pressure has been applied thereto which will deliver a hammer blow to the plunger 19. This will cause the tang 14 to snap from the wire forming the thread at the notch located at the base of the tang at the inner diameter of the thread.

What is claimed is:

1. In a device for removing a tang end of a thread within an aperture, a pair of telescoped inner and outer sleeves, a plunger and a piston supported within the inner sleeve with the latter extending from the protruding end of the sleeve, a spring within the inner sleeve in engagement with the piston and plunger, a spring within the outer sleeves engaging its closed end and the opposite end of the plunger from that engaged by the first said spring, said plunger having an annular flange with truncated conical camming surfaces in outward converging relationship, a plurality of balls in apertures through the wall of the inner sleeve in position to be retained in engagement with the flange to keep the plunger from moving when the spring in the outer sleeve is compressed, said outer sleeve inner wall having a radius of greater diameter each side of the diameter which holds the balls inwardly of the inner sleeve in engagement with the piston so that the balls may retract and be released from the piston at both ends of the outer sleeve.

2. In a device as recited in claim 1, wherein the spring between the plunger and piston has substantially less strength than the spring between the piston and the closed end of the outer sleeve.

3. In a device as recited in claim 1, wherein the exposed end of the outer sleeve supports a cushioning element for engagement with the surface of the element containing the threaded aperture.

4. In a device as recited in claim 1, wherein the outer sleeve has a collar secured thereto which engages a shoulder on the inner sleeve to limit the relative outward movement of the sleeves.

5. In a device as recited in claim 4, wherein the outer sleeve is of tubular form having a plug for closing the end opposite to that containing the collar.

6. In a device as recited in claim 1, wherein a second spring engages the closed end of the outer sleeve and an adjacent portion of the inner sleeve.

References Cited UNITED STATES PATENTS 2,455,270 11/1948 Ravella 17312O 2,594,901 4/1952 Forster 81-52.35

2,787,178 4/1957 Maxim 173119 3,181,626 5/1965 Sussman l73119 X 3,222,766 12/1965 Camargo 81--275 FOREIGN PATENTS 1,122,460 1/1962 Germany.

MILTON S. MEHR, Primary Examiner. 

